Investigations on the role of mitochondria-bound cytoplasmic ribosomes in yeast will be continued To determine if classes of nuclear-encoded mitochondrial proteins are synthesized on ribosomes bound to the outer mitochondrial membrane, bound and free mRNA will be isolated and purified. In vitro translation systems along with polyacrylamide slab-gel electrophoresis will be used to determine the nature of the produce synthesized. To examine possible mitochondrial regulatory phenomena, we will examine non-histone chromsomal proteins in yeast to search for putative regulatory species involved in regulation of mitochondrial biogenesis. To execute these experiments, we will take advantage of mutants defective in nuclear RNA synthesis which still retain mitochondrial transcription. The experiments are designed to test for a product or products of mitochondrial protein synthesis which interact with the nuclear genome. BIBLIOGRAPHIC REFERENCES: DNA-Binding Proteins Related to the Dosage of Specific Yeast Chromosomes, D.B. Finkelstein and R.A. Butow. Biochem. Biophys. Res. Commun. 66,1365 (1975)